How to set up a collection of abstract classes with JAXB for deserializetion in Jackson?

I have an entity structure, where one class, already a few levels down from the root of the tree, (PoFoconNetz) has a Set field, containing instances of an abstract class (PoFoconKnoten) with three possible implementations (PoBAC32, PoBAC12 and PoBAU).

The following annotations from the javax.xml.bind.annotation.* package are applied to the classes:

• To PoFoconNetz: @XmlSeeAlso({ PoBAC32.class, PoBAC12.class, PoBAU.class })
• To the Set<PoFoconKnoten> field in PoFoconNetz, called foconKnoten:

@XmlElementWrapper(name = "foconKnoten")
@XmlElements(value = {
	@XmlElement(name = "PoBAC32", type = PoBAC32.class),
	@XmlElement(name = "PoBAC12", type = PoBAC12.class),
	@XmlElement(name = "PoBAU", type = PoBAU.class) })

• To the abstract PoFoconKnoten class: @XmlSeeAlso({ PoBAC32.class, PoBAC12.class, PoBAU.class })
• To the three concrete subclasses: @XmlRootElement

On the sender side, these classes are serialized into XML using JAXB (2.3.0), in order to be sent to a REST endpoint, resulting in an XML like this:

<[...ROOT ITEMS OMITTED...]>
<foconNetz [...ATTRIBUTES...]>
	<foconKnoten>
		<PoBAC12 [...ATTRIBUTES...]>
			<[...FURTHER SUB-ITEMS...]>
		</PoBAC12>
	</foconKnoten>
</foconNetz>

Then, the receiver Spring application uses Jackson 2.9.9 to restore the original Java entities. Here the following parts could be relevant, as these are supposed to enable the processing of JAXB annotations:

	@Autowired
	private ObjectMapper jacksonObjectMapper;
[...]
	jacksonObjectMapper.registerModule(new JaxbAnnotationModule());
	jacksonObjectMapper.setAnnotationIntrospector(new 
		XmlJaxbAnnotationIntrospector(jacksonObjectMapper.getTypeFactory()));

But when the sent XML arrives on the receiver side, Jackson throws an error, complaining about the non-ability to instantiate a PoFoconKnoten, seemingly oblivious to the type information contained in the XML:

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `my.company.product.PoFoconKnoten` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
 at [Source: (PushbackInputStream); line: 1, column: 252] (through reference chain: [...VARIOUS OTHER CLASSES...]->my.company.product.PoFoconNetz["foconKnoten"]->java.util.HashSet[0])
	at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67) ~[jackson-databind-2.9.9.jar:2.9.9]

I'd love to receive any pointers about what could be the cause of the problem and how could I go about solving it.